LD modules are in wide use, each of which includes a semiconductor laser device (hereinafter referred to as an “LD”) and an optical fiber. Such an LD module causes a laser beam, emitted from the LD, to be coupled with the optical fiber. In recent years, development of high-output LD modules has been advanced by (i) increasing the number of LDs and/or (ii) achieving high output of each of the LDs.
For example, techniques disclosed in Patent Literatures 1 and 2 are each known as a technique for enhancing a reliability of an LD which achieved high output. According to the technique disclosed in Patent Literature 1, catastrophic optical damages (CODs) are prevented by treating an end surface of an LD with a treatment solution having a function of preventing a surface level from being generated. According to the technique disclosed in Patent Literature 2, an optical confinement coefficient (Γ factor) of an active layer is reduced by dispersing a light density, in a vertical direction, of the active layer.